System and method for anchoring a cord-like element to a workpiece

ABSTRACT

A novel system and method for anchoring a suture or other cord-like element to a bone or other workpiece. The system comprises a drill for forming an undercut hole in a bone or other workpiece, an anchor for securing a suture or other cord-like element in the undercut hole in the bone or other workpiece, and an inserter for deploying the anchor in the undercut hole in the bone or other workpiece.

RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.08/935,215 filed Sep. 22, 1997, now U.S. Pat. No. 5,885,294.

FIELD OF THE INVENTION

The field of art to which this invention relates is apparatus andmethods for anchoring a cord-like element to a workpiece, and morespecifically suture anchors for anchoring suture material to bone.

BACKGROUND OF THE INVENTION

As the treatment of injuries to joints and soft tissue has progressed inthe orthopedic medical arts, there has been a need for medical deviceswhich can be used to attach tendons, ligaments and other soft tissue tobone. When surgically repairing an injured joint, for example, it isoften preferable to restore the joint by reattaching the damaged softtissues rather than replacing them with an artificial material. Suchrestorations typically require the attachment of soft tissue such asligaments and tendons to bone.

An increase in the incidence of injuries to joints involving soft tissuehas been observed. This increased incidence may be due, at least inpart, to an increase in participation by the public in various physicalactivities such as sports and other recreational activities. These typesof activities may increase the loads and stress placed upon joints,sometimes resulting in joint injuries with corresponding damage toassociated soft tissue. In 1991, for example, there were approximately560,000 surgical procedures performed in the United States in which softtissue was attached to a bone in various joints including the shoulder,hip and knee.

One conventional orthopedic procedure for reattaching soft tissue tobone is performed by initially drilling holes or tunnels atpredetermined locations through a bone in the vicinity of a joint. Then,the surgeon approximates soft tissue to the surface of the bone usingsutures threaded through these holes or tunnels. This method, althougheffective, is a time-consuming procedure resulting in the generation ofnumerous bone tunnels. A known complication of drilling tunnels acrossbone is that nerves and other soft tissue structures may be injured bythe drill bit or orthopedic pin as it exits the far side of the bone.Also, it is anatomically very difficult to reach and/or secure asuture/wire that has been passed through a tunnel. When securing thesuture or wire on the far side of the bone, nerves and soft tissues canbecome entrapped and damaged.

In order to overcome some of the problems associated with the use of theconventional bone tunnel procedures, suture anchors have been developedand are frequently used to attach soft tissue to bone. A suture anchoris an orthopedic, medical device which is typically implanted into acavity drilled into a bone. Although less frequently, these devices havealso been referred to as bone anchors. The cavity is typically referredto as a bore hole and usually does not extend through the bone. Thistype of bore hole is typically referred to as a "blind hole". The borehole is typically drilled through the outer cortex layer of the bone andinto the inner cancellous layer. The suture anchor may be engaged in thebore hole by a variety of mechanisms including friction fit, barbs whichare forced into the cancellous layer of bone, etc. Suture anchors areknown to have many advantages including reduced bone trauma, simplifiedapplication procedures, and decreased likelihood of suture failure dueto abrasion on bone. Suture anchors may be used in the Bankart shoulderreconstruction for repairing the glenohumeral ligament and may also beused in surgical procedures such as rotator cuff repair and hipreplacement. Also, such anchors may be used in repair of tendon tears bydirect attachment of bone to bone.

Suture anchors typically have at least one suture attached. This may beby means of a hole or opening for receiving the suture(s). At least oneend and typically both ends of the suture strand extend out from thebore hole and are used to attach soft tissue. The suture anchorspresently described in the art may be made of absorbable materials whichabsorb over time, or they may be made from various non-absorbable,biocompatible materials. Although most suture anchors described in theart are made from non-absorbable materials, the use of absorbable sutureanchors may result in fewer complications since the suture anchor isabsorbed and replaced by bone over time. In addition, the use ofabsorbable suture anchors may reduce the likelihood of damage to localjoints caused by anchor migration.

Although suture anchors for attaching soft tissue to bone are availablefor use by the orthopedic surgeon, there is a constant need in this artfor novel suture anchors having improved performance characteristics.

It has now also been recognized that suture anchors may have applicationin fields other than orthopedics. By way of example but not limitation,suture anchors may be employed in a field such as plastic surgery tostabilize tissue to bone. In these non-orthopedic applications, thedeployment location of the suture anchor may necessitate that the sutureanchor be formed as small as possible. For example, the suture anchormay need to be deployed in a relatively small facial bone. At the sametime, however, the loads placed on such a suture anchor may be much lessthan the loads placed on an orthopedic suture anchor, thus giving riseto a range of different design considerations.

Thus there is also a need for improved suture anchors which may be usedin non-orthopedic applications, including plastic surgery and the like.

SUMMARY OF THE INVENTION

These and other objects of the present invention are achieved throughthe provision and use of a novel system and method for anchoring asuture or other cord-like element to a bone or other workpiece.

In one form of the present invention, the system comprises a drill forforming an undercut hole in a bone or other workpiece, an anchor forsecuring a suture or other cord-like element in the undercut hole in thebone or other workpiece, and an inserter for deploying the anchor in theundercut hole in the bone or other workpiece.

In one form of the present invention, the drill comprises a shaft havinga proximal end, a distal end and a first longitudinal axis; are-centering element attached to the distal end of the shaft, there-centering element including a distally-tapering portion centered on asecond longitudinal axis parallel to, but laterally spaced from, aprojection of the first longitudinal axis; a connecting member centeredon the second longitudinal axis, the connecting member having a proximalend and a distal end, the connecting member extending distally from there-centering member and being attached at the proximal end of theconnecting member to the distally-tapering portion such that theconnecting member and the distally-tapering portion together define abeveled corner centered on the second axis; and a substantiallycylindrical drill head centered on an axial projection of the firstlongitudinal axis, the drill head having a proximal end, a distalcutting tip, an outer surface defining cutting flute means extendingbetween the distal cutting tip and the drill head proximal end, and atransverse cross-section larger than the transverse cross-section of theconnecting member; the proximal end of the drill head beingeccentrically attached to the distal end of the connecting member.

In one form of the present invention, the anchor comprises a body ofresilient material including a longitudinal axis, a distal end, a distalportion adjacent to the distal end, a proximal end, a proximal portionadjacent to the proximal end, and an intermediate portion connecting thedistal portion to the proximal portion; the intermediate portion havinga transverse cross-section sized to fit within the smallest transversecross-section of the undercut hole in the workpiece; the proximal enddefining a substantially polygonal surface sized to contain an axialprojection of the transverse cross-section of the intermediate portion;the proximal portion tapering inwardly and distally from the proximalend so as to smoothly mate with the intermediate portion; the distalportion curving inwardly and distally from the intermediate portion tothe distal end, and the distal end defining a curved surface whichsmoothly mates with the distal portion; the distal portion and thedistal end together defining a substantially U-shaped groove extendingfrom a first groove end adjacent the intermediate portion and located inalignment with one corner of the proximal end to a second groove endadjacent the intermediate portion and located in alignment with anothercorner of the proximal end; the groove being sized to receive a lengthof the cord-like material therein; a first bore extending from the firstgroove end to the proximal end of anchor, parallel to the longitudinalaxis; a second bore extending from the second groove end to the proximalend of the anchor, parallel to the longitudinal axis; the first andsecond bores being sized to receive a length of the cord-like materialtherethrough; and a third bore extending into the proximal end of theanchor adjacent to another corner thereof, the third bore also beingparallel to the longitudinal axis and extending through at least theproximal portion of the anchor.

In one form of the present invention, the inserter comprises a handlecontaining a biasing element; a drive rod having a rod longitudinalaxis, a rod distal end, a rod proximal end, and an axial length, theproximal end of the drive rod being attached to the handle; and a sleevehaving a sleeve longitudinal axis, a sleeve proximal end, a sleevedistal end, and an axial length shorter than the axial length of thedrive rod; the sleeve being telescopically mounted co-axially over thedrive rod and in engagement with the handle and the biasing element suchthat the sleeve is normally biased toward a first position wherein thesleeve distal end is located distally of the rod distal end so as tocreate an open cavity adapted to receive and frictionally retain atleast a portion of the anchor, but may be moved proximally along thedrive rod against the biasing element to a second position wherein therod distal end projects axially and distally from the sleeve distal end.

In one form of the present invention, the method for forming an undercutbore in a workpiece comprises (a) providing a drill for forming anundercut hole in a workpiece, the drill comprising: a shaft having aproximal end, a distal end and a first longitudinal axis; a re-centeringelement attached to the distal end of the shaft, the re-centeringelement including a distally-tapering portion centered on a secondlongitudinal axis parallel to, but laterally spaced from, a projectionof the first longitudinal axis; a connecting member centered on thesecond longitudinal axis, the connecting member having a proximal endand a distal end, the connecting member extending distally from there-centering member and being attached at the proximal end of theconnecting member to the distally-tapering portion such that theconnecting member and the distally-tapering portion together define abeveled corner centered on the second axis; and a substantiallycylindrical drill head centered on an axial projection of the firstlongitudinal axis, the drill head having a proximal end, a distalcutting tip, an outer surface defining cutting flute means extendingbetween the distal cutting tip and the drill head proximal end, and atransverse cross-section larger than the transverse cross-section of theconnecting member; the proximal end of the drill head beingeccentrically attached to the distal end of the connecting member; (b)engaging the distal tip with the surface of the workpiece; (c) rotatingthe drill on the first longitudinal axis while urging the distal tiptoward the workpiece so as to form a substantially cylindrical bore inthe workpiece having a depth substantially equal to the axial length ofthe drill head plus the axial length of the connecting means; (d)further advancing the distal tip into the workpiece such that thebeveled corner engages the bore, thereby shifting the axis of rotationof the drill head form the first longitudinal axis toward the secondlongitudinal axis and causing the drill head to enlarge the diameter ofthe bore below a depth substantially equal to the axial length of theconnecting means; and (e) removing the drill head and the connectingmeans from the bore.

In one form of the present invention, the method for attaching an objectto a workpiece comprises the steps of: providing a bore in theworkpiece; providing a elastically compressible anchor having alongitudinal axis, a cross-section transverse to the longitudinal axislarger than the transverse cross-section of the bore adjacent thesurface of the workpiece, and means for attaching an object to theanchor; axially inserting the anchor into the bore so as to secure theanchor to the workpiece; and attaching the object to the anchor.

In one form of the present invention, the method for attaching a lengthof cord-like material within an opening in a workpiece comprises thesteps of:

(a) providing:

a length of cord-like material;

an anchor for securing a length of cord-like material in the undercuthole in the workpiece, the anchor comprising:

a body of resilient material including a longitudinal axis, a distalend, a distal portion adjacent to the distal end, a proximal end, aproximal portion adjacent to the proximal end, and an intermediateportion connecting the distal portion to the proximal portion;

the intermediate portion having a transverse cross-section sized to fitwithin the smallest transverse cross-section of the undercut hole in theworkpiece;

the proximal end defining a substantially polygonal surface sized tocontain an axial projection of the transverse cross-section of theintermediate portion;

the proximal portion tapering inwardly and distally from the proximalend so as to smoothly mate with the intermediate portion;

the distal portion curving inwardly and distally from the intermediateportion to the distal end, and the distal end defining a curved surfacewhich smoothly mates with the distal portion;

the distal portion and the distal end together defining a substantiallyU-shaped groove extending from a first groove end adjacent theintermediate portion and located in alignment with one corner of theproximal end to a second groove end adjacent the intermediate portionand located in alignment with another corner of the proximal end;

the groove being sized to receive a length of the cord-like materialtherein;

a first bore extending from the first groove end to the proximal end ofanchor, parallel to the longitudinal axis;

a second bore extending from the second groove end to the proximal endof the anchor, parallel to the longitudinal axis;

the first and second bores being sized to receive a length of thecord-like material therethrough; and

a third bore extending into the proximal end of the anchor adjacent toanother corner thereof, the third bore also being parallel to thelongitudinal axis and extending through at least the proximal portion ofthe anchor; and

an inserter for deploying a compressible anchor in the undercut hole inthe workpiece, the inserter comprising:

a handle containing a biasing element;

a drive rod having a rod longitudinal axis, a rod distal end, a rodproximal end, and an axial length, the proximal end of the drive rodbeing attached to the handle; and

a sleeve having a sleeve longitudinal axis, a sleeve proximal end, asleeve distal end, and an axial length shorter than the axial length ofthe drive rod;

the sleeve being telescopically mounted co-axially over the drive rodand in engagement with the handle and the biasing element such that thesleeve is normally biased toward a first position wherein the sleevedistal end is located distally of the rod distal end so as to create anopen cavity adapted to receive and frictionally retain at least aportion of the anchor, but may be moved proximally along the drive rodagainst the biasing element to a second position wherein the rod distalend projects axially and distally from the sleeve distal end;

(b) threading the length of cord-like material distally through thefirst bore in the anchor, through the groove in the anchor, andproximally through the second bore in the anchor;

(c) with the inserter in the first position, inserting the anchorproximal and first into the cavity at the distal end of the sleeve andretaining the anchor in the cavity by a frictional fit;

(d) engaging the distal end of the sleeve with the surface of theworkpiece immediately surrounding the undercut opening;

(e) exerting a driving force on the handle so as to move the sleeve fromits first position relative to the drive rod to its second positionrelative to the drive rod and to advance the distal end of the drive rodinto the opening pushing the anchor ahead of it, thereby elasticallydeforming the anchor; and

(f) removing the drive rod from the opening and the distal end of thesleeve from the surface of the workpiece.

In another form of the present invention, the method for attaching alength of cord-like material to a workpiece comprises the steps of:

(a) providing:

a length of cord-like material;

a drill for forming an undercut hole in a workpiece, the drillcomprising:

a shaft having a proximal end, a distal end and a first longitudinalaxis;

a re-centering element attached to the distal end of the shaft, there-centering element including a distally-tapering portion centered on asecond longitudinal axis parallel to, but laterally spaced from, aprojection of the first longitudinal axis;

a connecting member centered on the second longitudinal axis, theconnecting member having a proximal end and a distal end, the connectingmember extending distally from the re-centering member and beingattached at the proximal end of the connecting member to thedistally-tapering portion such that the connecting member and thedistally-tapering portion together define a beveled corner centered onthe second axis; and

a substantially cylindrical drill head centered on an axial projectionof the first longitudinal axis, the drill head having a proximal end, adistal cutting tip, an outer surface defining cutting flute meansextending between the distal cutting tip and the drill head proximalend, and a transverse cross-section larger than the transversecross-section of the connecting member;

the proximal end of the drill head being eccentrically attached to thedistal end of the connecting member;

an anchor for securing a length of cord-like material in the undercuthole in the workpiece, the anchor comprising:

a body of resilient material including a longitudinal axis, a distalend, a distal portion adjacent to the distal end, a proximal end, aproximal portion adjacent to the proximal end, and an intermediateportion connecting the distal portion to the proximal portion;

the intermediate portion having a transverse cross-section sized to fitwithin the smallest transverse cross-section of the undercut hole in theworkpiece;

the proximal end defining a substantially polygonal surface sized tocontain an axial projection of the transverse cross-section of theintermediate portion;

the proximal portion tapering inwardly and distally from the proximalend so as to smoothly mate with the intermediate portion;

the distal portion curving inwardly and distally from the intermediateportion to the distal end, and the distal end defining a curved surfacewhich smoothly mates with the distal portion;

the distal portion and the distal end together defining a substantiallyU-shaped groove extending from a first groove end adjacent theintermediate portion and located in alignment with one corner of theproximal end to a second groove end adjacent the intermediate portionand located in alignment with another corner of the proximal end;

the groove being sized to receive a length of the cord-like materialtherein;

a first bore extending from the first groove end to the proximal end ofanchor, parallel to the longitudinal axis;

a second bore extending from the second groove end to the proximal endof the anchor, parallel to the longitudinal axis;

the first and second bores being sized to receive a length of thecord-like material therethrough; and

a third bore extending into the proximal end of the anchor adjacent toanother corner thereof, the third bore also being parallel to thelongitudinal axis and extending through at least the proximal portion ofthe anchor; and

an inserter for deploying a compressible anchor in the undercut hole inthe workpiece, the inserter comprising:

a handle containing a biasing element;

a drive rod having a rod longitudinal axis, a rod distal end, a rodproximal end, and an axial length, the proximal end of the drive rodbeing attached to the handle; and

a sleeve having a sleeve longitudinal axis, a sleeve proximal end, asleeve distal end, and an axial length shorter than the axial length ofthe drive rod;

the sleeve being telescopically mounted co-axially over the drive rodand in engagement with the handle and the biasing element such that thesleeve is normally biased toward a first position wherein the sleevedistal end is located distally of the rod distal end so as to create anopen cavity adapted to receive and frictionally retain at least aportion of the anchor, but may be moved proximally along the drive rodagainst the biasing element to a second position wherein the rod distalend projects axially and distally from the sleeve distal end;

(b) forming an undercut hole in the workpiece with the drill by (1)engaging the distal tip of the drill head with the surface of theworkpiece, (2) rotating the drill on the first axis while advancing thedistal tip of the drill head into the workpiece to a depth equal to theaxial length of the drill head plus the axial length of the connectingmember, so as to form a substantially cylindrical bore in the workpiece,(3) advancing the distal tip further into the workpiece so as to forcethe beveled corner into the hole thereby causing the axis of rotation ofthe drill head to shift from the first longitudinal axis toward thesecond longitudinal axis and the drill head to radially enlarge theinner portion of the hole, and (4) removing the drill head and theconnecting member from the bore through the outer, unenlarged portion ofthereof;

(c) threading the length of cord-like material distally through thefirst bore in the anchor, through the groove in the anchor, andproximally through the second bore in the anchor;

(d) with the inserter in the first position, inserting the anchorproximal and first into the cavity at the distal end of the sleeve andretaining the anchor in the cavity by a frictional fit;

(e) engaging the distal end of the sleeve with the surface of theworkpiece immediately surrounding the undercut hole;

(f) exerting a driving force on the handle so as to move the sleeve fromits first position relative to the drive rod to its second positionrelative to the drive rod and to advance the distal end of the drive rodinto the undercut hole pushing the anchor ahead of it, therebyelastically deforming the anchor as it passes through the non-enlargedportion of the undercut hole and allowing the anchor to expand to itsoriginal shape upon the completion of its entry into the enlargedportion of the undercut hole; and

(g) removing the drive rod from the undercut hole and the distal end ofthe sleeve from the surface of the workpiece.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other objects and features of the present invention will bemore fully disclosed or rendered obvious by the following detaileddescription of the preferred embodiments of the invention, which are tobe considered together with the accompanying drawings wherein likenumbers refer to like parts, and further wherein:

FIG. 1 is a perspective view of a drill formed in accordance with thepresent invention;

FIG. 2 is a perspective view of an anchor formed in accordance with thepresent invention, with a cord-like element attached thereto;

FIG. 3 is a perspective view of an inserter device for deploying theanchor shown in FIG. 2;

FIGS. 4-7 are detailed views of the drill shown in FIG. 1;

FIGS. 8-10 show the drill of FIG. 1 forming an undercut hole in aworkpiece;

FIGS. 11-15 are detailed views of the anchor shown in FIG. 2;

FIGS. 16-27 are detailed views showing various aspects of the inserterdevice of FIG. 3; and

FIGS. 28-33 show the inserter device of FIG. 3 deploying the anchor ofFIG. 2 in a workpiece.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

As discussed above, the present invention comprises a novel system andmethod for anchoring a suture or other cord-like element to a bone orother workpiece. More particularly, the novel system includes a drill100 generally shown in FIG. 1, an anchor 300 generally show in FIG. 2,and an anchor insertion device 500 generally shown in FIG. 3. The methodgenerally includes the steps of forming an undercut hole in theworkpiece and locating an anchor (with a cord-like element attachedthereto) securely within the hole, as will be discussed in detail below.

Referring specifically to FIGS. 1 and 4-7, it will be seen that drill100 includes a shaft 105 and a drill head 110.

Shaft 105 has a shaft distal end 112, a shaft proximal end 115, acentral longitudinal axis 195, and a re-centering element 125 attachedto shaft distal end 112. The shaft proximal end 115 terminates in aportion 130 which is configured to be received in the chuck of a powerdrill or the like (not shown). Alternatively, in the event that drill100 is to be hand driven, rather than power driven, portion 130 may beconfigured in the form of a handle.

Re-centering element 125 includes a central, substantially cylindricalportion 135 having a longitudinal axis aligned with shaft longitudinalaxis 195, and a proximally-tapering portion 145 attached to shaft distalend 112 and having a longitudinal axis aligned with shaft longitudinalaxis 195. Re-centering element 125 also comprises a distally-taperingportion 155 attached to a distally-extending connecting portion 160.Distally-tapering portion 155 and distally-extending connecting portion160 are centered about a longitudinal axis 120. Longitudinal axis 120 islaterally offset from longitudinal axis 195 in the manner shown in FIG.6. The angle of taper of proximally-tapering portion 145 relative tolongitudinal axis 195 is substantially smaller than the angle of taperof distally-tapering portion 155 relative to longitudinal axis 120.Distally-tapering portion 155 and connecting portion 160 together definea beveled corner 170 at their intersection. Beveled corner 170 is alsocentered about longitudinal axis 120, which longitudinal axis islaterally offset from the above-mentioned longitudinal axis 195.Preferably beveled corner 170 comprises a radius. Re-centering element125 also preferably defines a cutting flute 175 which extends from shaftdistal end 112 to connecting portion 160, i.e., throughproximally-tapering portion 145, cylindrical portion 135,distally-tapering portion 155 and beveled corner 170.

Drill head 110 is connected to the distal end of connecting portion 160.Drill head 110 has a drill head proximal end 180 and a drill head distalend 190. Drill head 110 is centered about the aforementionedlongitudinal axis 195. Drill head 110 also includes an outer surface 200defining a distal cutting tip 205 at drill head distal end 190, and atleast one, and preferably a pair, of cutting flutes 210 extending fromcutting tip 205 to drill head proximal end 180.

The diameter of connecting portion 160 is selected to be smaller thanthe diameter of drill head 110, such that when drill head 110 isattached to connecting portion 160, an edge 220 of drill head 110,located between an adjacent pair of cutting flutes 210, is located on anaxial projection of the aforementioned cutting flute 175.

As will hereinafter be described in greater detail, the foregoing drill100 may be conveniently used to form an undercut hole in a piece of boneor other workpiece. More specifically, the distal cutting tip 205 may beplaced against a surface 221 of the workpiece 225 (FIG. 8), and thedrill head 100 may be rotated on its longitudinal axis 195. This willcause drill head 110 to form an initial bore 227 in the workpiece (FIG.9). When this bore 227 reaches a depth equal to the axial length ofdrill head 110 plus the axial length of connecting portion 160, however,the beveled corner 170 will engage the edge 226 of the bore 227 at thesurface 221 of the workpiece. In this respect it is to be appreciatedthat the longitudinal axis 120 of the beveled corner 170 is laterallyoffset from the shaft's longitudinal axis 195. Accordingly, as the drillhead continues to advance into the workpiece, the axis of rotation ofdrill head 110 will shift laterally from the shaft's longitudinal axis195 to the beveled corner's longitudinal axis 120. The effect will be togradually force the movement of drill head 110 laterally so as toundercut the workpiece and form a second bore 228 at a depthsubstantially equal to the axial length of connecting portion 160 plusbeveled corner 170 (FIG. 10). It should also be appreciated that as thisoccurs, cutting flute 175 of the re-centering element 125 will from acountersunk portion at the opening of bore 227.

Referring next to FIGS. 2 and 11-15, it will be seen that the anchor 300comprises a block of material having natural resiliency. This blockcomprises a body 305 which includes a distal end 310, a distal portion325 adjacent to the distal end 310, a proximal end 326, a proximalportion 327 adjacent to the proximal end 326, and an intermediateportion 330 connecting distal portion 325 to proximal portion 327.

More particularly, intermediate portion 330 has a substantiallycylindrical cross-section having a diameter slightly smaller than thediameter of drill head 110. The distal portion 325 curves inwardly fromintermediate portion 330 to curved distal end 310. Further, distal end310 and distal portion 325 together define a groove 335 (FIG. 11) whichextends from a first end 340 (FIG. 13) (adjacent one side 345 of isintermediate portion 330), across distal end 310 to a second end 355(adjacent another side 360 of intermediate portion 330). Groove 335 isadapted to receive a suture or other cord-like element 365 (FIG. 2) bentin a substantially U-shaped configuration.

Bores 370, 375 (FIG. 12) extend from groove ends 340 and 355,respectively, to proximal end 326, parallel to the longitudinal axis 380(FIG. 13) of body 305. Bores 370 and 375 each have a cross-sectionalsize and shape adapted to accommodate the suture or other cord-likeelement 365. Hence, the suture or other cord-like element 365 may bethreaded through bore 370, across groove 335 and back through bore 375(see FIG. 2). Preferably bores 370 and 375, and the suture or othercord-like element 365, are sized so that the suture or other cord-likeelement does not completely fill, in a diametrical sense, bores 370 and375.

The proximal end 326 of the anchor is substantially rectangular inshape, such that an axial projection of the circular cross-section ofintermediate portion 330 will fit within the boundaries of rectangularproximal end 326. Accordingly, it will be understood that proximalportion 327 of body 305 tapers inwardly from corners 385, 390, 395 and400 (FIG. 14) of proximal end 326, respectively, so as to smoothly matewith intermediate portion 330. In view of this construction, sutureanchor 300 essentially has four projections or lobes projecting radiallybeyond the circumference of the anchor's intermediate portion 330.Preferably the walls extending between corners 385, 390, 395 and 400 arecurved slightly so as to form curved lobes projecting radially beyondthe anchor's intermediate portion 330. In one preferred form of theinvention, each of the walls extending between the corners 385, 390, 395and 400 comprise a radius.

The openings of bores 370 and 375 onto proximal end 326 are locatedadjacent to opposite corners 390 and 400, respectively, further, bores415 and 420 extend into proximal end 326 adjacent to opposite corners385 and 395, respectively. Bores 415 and 420 need not necessarily extendall the way through body 305. Thus, as shown in the drawings, bores 415and 420 extend from the proximal end 326 of body 305 parallel to oneanother, and parallel to the anchor's longitudinal axis 380, to closedends located in intermediate portion 330 of body 305.

Since the suture or other cord-like element 365, extending through bores370 and 375, does not completely fill bores 370 and 375, and since thesuture or other cord-like element 365 is generally formed of a wovenmaterial which may be compressed, it will be seen that the naturalplasticity of the anchor material, together with longitudinal bores 370,375, 415 and 420, allow the proximal, generally rectangularcross-section of the body to be substantially elastically compressed.Accordingly, anchor body 305 may be easily compressibly deformed so asto fit through the outer portion 227 of the undercut hole formed by thedrill 100 in workpiece 225, and thereafter allowed to elastically expandto its normal shape within the undercut portion 228 of the hole so as tosecurely anchor the suture or other cord-like element 365 to theworkpiece. By placing one of the holes 370, 375, 415 and 420 next toeach of the corners 385, 390, 395 and 400, space is provided within thebody of the anchor for the corners to deflect radially inwardly duringanchor insertion. This helps prevent the anchor from deforminglongitudinally during anchor insertion.

By way of example but not limitation, anchor 300 may be formed out of anon-absorbable polymer such as polysulfone or an absorbable polymer suchas polylactic acid (PLA).

A specialized inserter device 500 has been found to be particularlyuseful in the emplacement of an anchor as just described into anundercut hole in a workpiece. This inserter device 500 is generallyshown in FIG. 3, and more particularly illustrated in FIGS. 16-27.

Inserter device 500 includes a handle 505 (FIGS. 3 and 16-18), a driverod 510 (FIGS. 3 and 19-22), a sleeve 515 (FIGS. 3 and 23-27), andbiasing means 520 (FIG. 3).

More specifically, as representatively shown in FIGS. 16-18, the handle505 may conveniently be made in two identical halves 525. In itsassembled form, handle 505 defines a drive rod mounting cavity 535, asleeve/biasing means mounting cavity 540, and a sleeve/drive rod exitportal 545.

The drive rod 510, shown particularly in FIGS. 19-22, includes a shaft550 having a distal end 555 and a proximal end 560, an enlarged proximalportion 565 attached to the proximal end 560, and an elongated tipportion 570 attached to the distal end 555. The enlarged proximalportion 565 is sized to fixedly engage the drive rod mounting cavity 535in handle 505, with the shaft 550 extending outwardly therefrom throughsleeve/biasing means mounting cavity 540 and exit portal 545. Theelongated tip portion 570 has a smaller diametric cross-section thanshaft 550, and shaft 550 and elongated tip portion 570 have a commonlongitudinal axis 575. Further, elongated tip portion 570 defines a pairof opposing longitudinal grooves 580 (FIG. 22) in its outer surface 585which preferably extend along substantially the entire length ofelongated tip portion 570. The grooves 580 are sized to receive thesuture or other cord-like element 365 threaded through anchor body 305.

The biasing means 520, in the preferred embodiment of the invention, isa coil spring. The coil spring is located in sleeve/biasing meansmounting cavity 540, co-axially surrounding shaft 550 of drive rod 510,and in engagement with the proximal shoulder 590 (FIG. 16) of cavity540.

The sleeve 515, shown particularly in FIGS. 23-27, includes anelongated, hollow tubular member 595, a proximal end 600, aradially-extending flange 605 surrounding the tubular member at itsproximal end, a distal end 610, and a reduced diameter portion 615adjacent to its distal end. The reduced diameter portion 615 defines apair of opposing longitudinal slots 620 (FIG. 27) extending proximallyfrom the distal end 610 for substantially the entire length of reduceddiameter portion 615. The transverse width of slots 620 is such that thesuture or other cord-like element 365 may be slidably received therein.

The sleeve 515 is disposed in telescoping relation over the drive rodshaft 550, with the sleeve's flange 605 located in the sleeve/biasingmeans mounting cavity 540, between the distal end of spring 520 and theforward end surface 621 (FIG. 16) of cavity 540, such that tubularmember 595 is slidingly received in portal 545.

Thus it will be understood that handle 505 and drive rod 510 togetherform a substantially integral subassembly, with sleeve 515 adapted toreciprocate relative to the drive rod. In this regard it will beunderstood that the relative lengths of drive rod shaft 550 and tubularmember 595 are selected such that, in their "normal" (i.e., with tubularmember 595 in its outwardly-biased) position, the sleeve's reduceddiameter portion 615 is disposed distally of the distal end of the tipportion 570 of the drive rod 510. This defines a cavity in the distalend of the inserter device 500 into which the anchor 300 may be placedand maintained by a frictional fit. At the same time, the sleeve's slots620 permit a suture or other cord-like element 365 attached to theanchor to exit the sleeve.

Accordingly, once the undercut hole in the workpiece has been formed bydrill 100, the inserter device 500, with anchor 300 located within itsdistal end and with the suture or other cord-like element 365 threadedthrough the anchor and extending outwardly through the slots 620, may beused to insert the anchor into the undercut portion of the hole. Moreparticularly, the distal end 610 of the sleeve may be brought intoengagement with the surface 221 of the workpiece surrounding the upperbore 226 (FIGS. 28-31). Then, by pushing downwardly on the handle, thebiasing force tending to hold the sleeve in its extended position may beovercome, thereby allowing the tip portion of the drive rod to engagethe anchor and to drive it through upper bore 227 and down into theundercut portion 228 of the hole (FIGS. 32 and 33).

In so doing, the free ends of the suture or other cord-like element 365enter the grooves 580 in drive rod 510 so as to avoid being crushed orbroken during anchor deployment into the workpiece hole. At the sametime, the resilient nature of anchor 300, in concert with thelongitudinal bores 370, 375, 415 and 420 formed therein, allow theanchor to elastically collapse inwardly on itself far enough to passthrough the smaller portion 227 of the hole and then re-expand to itsnormal shape at the undercut portion 228 of the workpiece hole, therebylocking the anchor securely in the workpiece.

The foregoing concepts will be more fully understood by the followingdescription of an example of the system and method of the presentinvention in a medical context.

Looking now to FIGS. 8-10 and 28-33, an example of the use of theinvention to attach a length of suture 365 to a bone 225 is shown. Inthis context it should be understood that the nature of bone is suchthat the formation of an urdercut hole is not always necessary. This isbecause some bones have natural internal cavities (e.g., the head of thetibia, the humeral head, etc.), and other types of bone have softcancellous interiors distal to the outer cortical layer. In such asituation, an ordinary single-diameter bore may be formed in the bone.For the sake of the present description, however, it will be assumedthat an undercut hole will be formed in the bone. With thisunderstanding in mind, the method of the present invention may includethe following steps.

First, an undercut hole is formed in the bone 225 using a drill 100substantially as described above. Specifically, the distal cutting tip205 of the drill head 110 is placed against the location on the surface221 of bone 225 where it is desired to attach suture 365 (FIG. 8). Thedrill head 110 is then rotated about its longitudinal axis 195 whilebeing urged axially toward the bone so as to cut into the bone (FIG. 9).This causes the drill head 110 to form a substantially cylindrical hole227 in the bone.

Once the depth of the hole in the bone reaches a depth equal to theaxial length of the drill head 110 plus the axial length of theconnecting portion 160, the beveled corner 170 will engage the outeredge 226 of the hole. Thereafter, as the drill head is advanced furtherinto the bone, its axis of rotation will be gradually shifted fromlongitudinal axis 195 to the longitudinal axis 120 by the tendency ofthe beveled corner 170 to center itself relative to the outer edge 226of the hole. At the same time, the cutting flute 175 of re-centeringelement 125 will engage the outer edge 226 of the bone hole. The resultof this is that the drill head 110 will gradually shift laterally so asto increase the diameter of the hole at a depth equal to the axiallength of the connecting portion 160, while the cutting flute 175countersinks the outer end of the hole. Thus, once the depth of the holeis equal to the axial length of the drill head 110 plus the connectingportion 160 plus the axial length of the beveled corner 170, the holewill have an outer portion 227 (FIG. 10) having a first diameter and aninner portion 228 having a second diameter larger than the firstdiameter.

The rotation of the drill 100 is then stopped and the shaft 105 ismanipulated so as to align drill head 110 with the outer portion 227 ofthe hole. The drill head 110 may then be withdrawn from the hole.

A length of suture 365 is then threaded distally through bore 370 ofanchor 300, across groove 335, and then proximally back through bore375. The resulting anchor/suture assembly is then inserted, proximal endfirst, into the reduced diameter portion 615 of sleeve 515, with thefree ends of suture 365 extending outwardly through slots 620. Theanchor is held in this position by a friction fit. In this condition,the resulting inserter/anchor assembly is ready for use in deploying theanchor into the undercut portion of the bone hole.

If desired, the aforementioned inserter/anchor assembly may bepre-assembled at the time of manufacture and then packaged in a sterilepackage, with the sterile package being opened in the operating room atthe time of use.

Anchor 300 is deployed in the bone hole by bringing the distal end ofsleeve 515 into engagement with the surface of the bone adjacent thehole (FIGS. 28-31). With the sleeve so positioned, a driving force isexerted distally on handle 505. Since the sleeve is fixed relative tothe bone, this driving force causes the sleeve 515 to slide proximallyin cavity 540, against the biasing spring 520, and forces the elongatedtip portion 570 of drive rod 510 into the hole, pushing anchor 300 aheadof it (FIG. 32 and 33).

As mentioned previously, the diameter of outer portion 227 of the bonehole is only slightly larger than the diameter of the intermediateportion 330 of anchor 300, and the proximal end 326 of anchor 300 has agenerally rectangular shape large enough to contain an axial projectionof intermediate portion 330. Hence, as the tapered distal portion 325,and intermediate portion 330, of anchor 300 enter the bone hole, theytend to align the anchor 300 with the hole. Thereafter, as drive rod 510continues to force anchor 300 into the hole, the proximal portion of theanchor is distorted (i.e., compressed) inwardly so as to fit within theouter portion 227 of the hole. This is made possible by the resilienceof the material used to form anchor 300, and by the presence of bores370, 375, 415 and 420 adjacent to the four corners of the proximalportion of anchor 300.

More specifically, bores 415 and 420 are empty and extend through theproximal portion of anchor 300 into the intermediate portion thereof.This helps allow the proximal portion of anchor 300 to compressinwardly. Bores 370 and 375, on the other hand, are not empty, butrather contain suture 365. Nevertheless, since bores 370 and 375 arelarger in diameter than suture 365, and since the suture is generallyformed out of a woven material such that it may be radially compressed,bores 370 and 375 also help allow the proximal portion of the anchor tocompress inwardly.

Once the proximal end of the anchor passes through the outer portion 227of the hole, and into inner portion 228, the proximal portion of theanchor elastically returns to its original shape. Therefore, since theoriginal shape of the anchor is too large to pass through the outerportion 227 of the bone hole, the anchor effectively and securelyanchors the suture within the bone. Thereafter, inserter 500 may beremoved, leaving the free ends of suture 365 extending out of the hole.This suture may then be used to attach tissue (or some other object) tothe bone.

In the above regard, it is desirable that (a) the drive rod 510 exertforce against as much of the proximal end of the anchor as possible, and(b) the suture not be crushed or damaged during the anchor insertionoperation. The exertion of the driving force against as much of theproximal end of the anchor as possible helps keep the anchor fromdeviating from the longitudinal axis of the outer portion 227 of thehole during deployment. Hence, each of the corners of the large proximalend of the anchor will tend to deflect substantially equally inwardly,and the anchor will not tend to twist and bind in the outer portion 227of the hole during insertion. To accomplish this, the elongated tip ofthe drive rod typically has a transverse cross-section of the sameshape, but slightly smaller than, the transverse cross-section of theouter portion 227 of the hole. However, in order to protect the sutures,the elongated tip portion of the drive rod also has a pair of opposinggrooves 580 in its outer surface. These grooves are sized to receive thefree ends of the suture extending from the anchor while the elongatedtip of the drive rod is located within the outer portion of the bonehole.

In the foregoing description of anchor 300, the proximal end 326 of theanchor is described as being substantially rectangular, with fourcorners 385, 390, 395 and 400, and with one of the bores 370, 375, 415and 420 being positioned next to one of the corners 385, 390, 395 and400. However, the proximal end 326 of anchor 300 could also be formedwith some other polygonal shape, e.g., substantially triangular, inwhich case only three corners would be provided, and only one hole 415,420 would be provided, in addition to the two suture holes 370, 375.Alternatively, the proximal end 326 of anchor 300 could be formed with apentagonal shape, i.e., with five corners, in which case three holes415, 420 would be provided, in addition to the two suture holes 370,375; or the proximal end 326 of anchor 300 could be formed with ahexagonal shape, in which case four holes 415, 420 would be provided, inaddition to the two suture holes 370, 375, etc. Preferably there areexactly as many holes 370, 375, 415 and 420 as there are corners to theproximal end 326 of anchor 300, with one hole aligned with each corner.In this way, appropriate space will be provided within the body of theanchor, into which the corners may radially deflect during insertion, soas to keep the body of the anchor from permanently deforminglongitudinally during deployment.

It is also anticipated that the proximal end 326 of anchor 300 could beformed with a non-polygonal shape, e.g., circular or elliptical, inwhich case an appropriate number of holes 415, 420 are formed in theanchor in addition to the two suture holes 370, 375.

It should also be appreciated that cutting flute 175 might be omittedfrom drill 100 if desired.

Furthermore, it should be appreciated that, if desired, drill 100 mightbe removed from the bone hole while still rotating.

It should also be appreciated that the undercut hole might be formed inthe bone or other workpiece using apparatus other than drill 100.

Also, the anchor 300 might be set in the bone or other workpiece usingapparatus other than inserter device 500.

Having thus described an illustrative preferred embodiment of the systemand method of the present invention, numerous modifications, variations,alterations and the like will occur to those skilled in the art. It is,therefore, intended that the foregoing specification be considered onlyas illustrative of the present invention, and that the invention belimited only by the terms of the appended claims.

What is claimed is:
 1. An inserter for deploying a compressible anchorin an undercut hole in a workpiece, said undercut hole comprising asmaller diameter portion and a larger diameter portion, said insertercomprising:a handle containing a biasing element; a drive rod having arod longitudinal axis, a rod distal end, a rod proximal end, and anaxial length, said proximal end of said drive rod being attached to saidhandle; and a sleeve having a sleeve longitudinal axis, a sleeveproximal end, a sleeve distal end, and an axial length shorter than anaxial length of said drive rod; said sleeve being telescopically mountedcoaxially over said drive rod and in engagement with said handle andsaid biasing element such that said sleeve is normally biased toward afirst position wherein said sleeve distal end is located distally ofsaid rod distal end so as to create an open cavity to receive andfrictionally retain at least a portion of the anchor, but may be movedproximally along said drive rod against said biasing element to a secondposition wherein said rod distal end projects axially and distally fromsaid sleeve distal end; and wherein said handle includes an internalcavity and an exit portal, said drive rod extends through said cavityand exits said portal, said biasing element comprises a coil springretained within said cavity and surrounding a portion of said drive rodextending through said cavity, and said sleeve includes a radial flangeadjacent to said sleeve proximal end, said sleeve extending through saidexit portal in sliding relation therewith such that said flange isretained within said cavity and engages one end of said spring.
 2. Aninserter according to claim 1 wherein said sleeve defines a least a pairof longitudinal slots extending from said sleeve distal end toward saidsleeve proximal end, said slots being sized to receive a length ofcord-like material attached to an anchor disposed in said cavity.
 3. Aninserter according to claim 1 wherein said drive rod includes anaxially-aligned portion adjacent to said rod distal end, saidaxially-aligned portion having a transverse cross-section sized to fitwithin the diameter of the smaller diameter portion of said undercuthole and an axial length slightly longer than a depth of the smallerdiameter portion of said undercut hole.
 4. An inserter according toclaim 3 wherein said axially-aligned portion has an outer surface anddefines at least a pair of longitudinal grooves extending from said roddistal end toward said rod proximal end, each said groove being sized toreceive a length of cord-like material attached to the anchor.